Technical Field
The present invention relates to a capacitance-type sensor sheet used for measuring an amount of stretch deformation and strain and/or distribution of stretch deformation and strain, and a method for manufacturing the capacitance-type sensor sheet.
Background Art
The capacitance-type sensor sheet can detect a concavo-convex shape of a measuring object from changes in capacitance between a pair of electrode layers, and can be used for contact-pressure distribution sensors and sensors such as a strain gage. In general, the capacitance in a capacitance-type sensor is represented by the following formula (1):C=∈0∈rS/d  (1)In the above formula, C represents a capacitance, ∈0 represents a dielectric constant in a free space, ∈r represents a relative dielectric constant of a dielectric layer, S represents an area of the electrode layer, and d represents a distance between electrodes.
Conventionally, as the above-mentioned sensor sheet, a sheet having a structure, in which a dielectric layer is sandwiched between a pair of electrode layers containing an elastomer having conductive fillers compounded, is known (refer to Patent Document 1). In the sensor sheet, the change in capacitance is large since the dielectric layer is an elastomer.
However, while the capacitance-type sensor sheet used for the contact-pressure distribution sensor is required to have excellent following properties to the deformation or action of a measuring object, the capacitance-type sensor sheet described in the above document cannot adequately satisfy this characteristic. Moreover, a capacitance-type sensor sheet, which is used for a sensor for measuring the amount of stretch deformation and strain and/or the distribution of stretch deformation and strain, is required to have such excellent endurance that the delamination between the electrode layer and the dielectric layer hardly occurs and the electric conductivity of the electrode layer is less reduced (electric resistance is less increased) even when the sensor sheet undergoes large stretch deformation or cyclic deforming.